1. Field of the Invention
The invention relates to an upper tool support for a stamping machine or the like having at least one stamping tool, preferably several stamping tools adjacently located, each stamping tool preferably comprising a punch, a punch support and a retaining nut connecting the punch with the punch support, and having a support body, a receiving plate with a tool guide for each stamping tool extending in the direction of stamping. The upper end of the stamping tool is limited in one direction by support flanges, and is being movably guided in the direction of stamping. A receptacle for the upper end of the stamping tool is provided on the support body above the tool guide and below a power transfer area. The receptacle is bridged by means of a power transfer rod which is generally movable in a direction vertical to the stamping direction. A lifting lever provided on the support body is associated with the stamping tool and laterally engages the upper end of the associated stamping tool from below. The upper end of the stamping tool is actively liftable into the receptacle by means of the lifting lever when the power transfer rod is pulled back.
2. The Prior Art
The following explanations basically relate not only to the upper tool supports of machine tools in the form of stamping machines, but also, for example, to cases where a ratchet-driven tool is disposed in the upper tool support. The teaching of the invention thus is not limited to a stamping machine and stamping tools, but applies to all machine tools in which comparable problems exist. In order to facilitate the understanding of the teaching, the teaching of the invention is described here and below by means of a preferred exemplary embodiment of an upper tool support for a stamping machine.
In a known upper tool support for a stamping machine from out of which the present invention arises (EP-A-No. 0 180 146 or respective prior public use), a quick change of a stamping tool and/or of all stamping tools is possible, but generally has limited space where several stamping tools are located next to each other. This is particularly true where a receiving plate is a part of the support body and where the tool guides are open in the direction towards the front of the support body, in which the upper ends of the stamping tools can be generally pushed into or placed horizontally in the tool guides. A locking cap locks all tool guides together at the open ends. By means of application of the locking cap which is then locked, the open ends of all tool guides in the receiving plate are locked in one step. Thus all stamping tools are secured. For this purpose the individual ends of the stamping tools are provided with hammerhead-like enlargements, and the receiving plate and the locking cap are provided with support flanges corresponding to the hammerhead-like enlargements, so that the stamping tools cannot slip downward out of the tool guides. The locking cap is pivotably fastened on the support body, or on the receiving plate via a pivot axle, and is lockable respectively with the support body or the receiving plate by means of a locking device disposed on the opposite lateral side. The locking device has a locking bolt pivoting in the horizontal plane on the receiving plate and a bolt receptacle provided on the locking cap and open on one side, the locking bolt being pivotable into the bolt receptacle and fixable by means of an adjusting nut for locking. Furthermore, receptacles for the upper ends of the stamping tools are provided in the support body above the tool guides and below a power transfer area, and these receptacles can be bridged by means of power transfer rods generally movable perpendicular to the stamping direction. With each stamping tool is associated a lifting lever, one end of which laterally engages the upper end of the associated stamping tool from below, so that the upper end of the stamping tool can be lifted into the receptacle by means of the lifting lever when the power transfer rod is pulled back. Pneumatic drives or the like, not further described, are provided for this purpose.
In accordance with the state of the art, known from the prior public use, the lifting of the stamping tool into the receptacle at the time the power transfer rod is pulled back is accomplished by forced control of the lifting lever. For this purpose the lifting lever is in the shape of a two-armed lever which is pivotably fixed on the support body below the power transfer rod by means of a pivot axle. The arm of the lifting lever pointing away from the receptacle is provided with a lift control surface which alternately acts with the side of the power transfer rod oriented away from the receptacle. If the power transfer rod is pulled out of the receptacle, the side of the power transfer rod oriented away from the receptacle glides onto the lift control surface of the lifting lever and thereby pushes this arm of the lifting lever downwards. The other, opposite arm of the lifting lever is correspondingly raised and the upper end of the stamping tool and thus the entire stamping tool is raised with it. When the side of the power transfer rod oriented away from the receptacle crosses the arm of the lifting lever, the end position of the punch in the receptacle is thus defined by the underside of the power transfer rod.
If the power transfer rod is then pushed forward again in the direction of the receptacle, the rear arm of the lifting lever is freed again. The stamping tool sinks downward out of the receptacle by its own weight and carries along with its upper end the arm of the lifting lever which is located there.
In practical use it has been shown that the lowering of the stamping tool by its own weight is not sufficiently dependable. It can sometimes happen that the stamping tool gets hung up in the tool guide so high that the upper end remains in the receptacle. The power transfer rod which is being pushed forward by the control drive meets the side of the upper end of the stamping tool and completely jams it.